In the route delivery industry, where a truck driver makes numerous deliveries to individual customers and locations, it is necessary for the driver to make a record of the delivery and to provide a delivery ticket or invoice to the customer along with the goods delivered. The traditional method of accomplishing this task is through the handwritten creation of an invoice or delivery ticket which is then torn from the invoice book or ticket book, as the case may be, and is then provided to the customer.
In recent years, improvements in the traditional method have been developed wherein an electronic device is mounted within the truck driver's vehicle which will provide invoices or delivery tickets by printing means. In such cases, a calculating machine is provided with a keyboard and printing mechanism so that the driver may enter the customer information, the quantity delivered, pricing and other information, and thereby to create in printed form an invoice to present to the customer, while also creating a permanent copy for retention by the driver for submission to the accounting department at the home office at the end of the route.
Later developments in the route delivery industry have led to devices which are handheld which may be carried with the driver into the customer's facility so that order entry information or other data may be entered by the driver while examining the customer's preexisting inventory, or while discussing the customer's needs with the customer's representatives.
Existing devices of this sort provide a small display, usually of two or four lines of sixteen characters each, with a limited electronic memory. Existing devices are frequently equipped with nickel-cadmium or other rechargeable batteries for power, though some devices operate with non-rechargeable batteries.
Since alkaline or other non-rechargeable batteries are likely to vent gaseous or liquid substances when recharging attempts are made upon such batteries, some feature must be provided on the device to prevent such misuse, while allowing the recharging of proper rechargeable batteries. With some existing devices which have recharging circuitry contained in them, cautionary language is provided on the case of the unit or in the operating instructions.
In other units, no recharging circuitry is provided and therefore the rechargeable batteries must be removed from the hand-held unit and recharged exteriorly of the unit. After recharging is completed, the user must re-install the batteries, taking care to install them in the proper orientation.
In other devices containing recharging circuitry, an external user operated switch of the slide or toggle variety is provided on the exterior of the unit's case such that the user can change the switch to disable the recharge circuitry when non-rechargeable batteries are in the unit, or to enable the recharging circuitry when rechargeable batteries are installed in the unit. This requires the user to remember to set the switch correctly when batteries are placed in the unit.
In order to effectuate recharging of internally mounted rechargeable batteries in existing units, the internal recharging circuitry of the hand-held unit must be provided with externally mounted connectors to engage a source of recharging power. Existing units are provided with connectors of the pin and socket variety, commonly the well-known D-sub variety where a generally D-shaped shell houses a plurality of pins and sockets which mate with complementing elements of external devices intended to be interconnected thereto. Due to the pin and socket architecture, care must be taken that interconnection is accomplished accurately and that damage to the pin and socket elements does not occur when interconnection is made or when the connector is not connected. Because hand-held units are repeatedly handled in varying environments, it is common for damage to, or contamination of, the pins or sockets to occur. Repair and maintenance of the connectors is necessarily undertaken at a repair facility in that event.
The internal circuitry of known devices is provided with a central processing integrated circuit element, having random access dynamic memory associated therewith, with interface circuitry to the keyboard and display and with circuitry to enable communication of the gathered data within the unit with external computing devices. The communication circuitry used in known devices allows communication with a single external unit through a standard protocol promulgated by the Electronic Industries Association (E.I.A.) known as RS-232C. No provision is made in existing hand-held route delivery data entry terminal devices for the addition of auxiliary memory devices or for intercommunication with devices other than those which communicate on the RS-232C protocol.
The construction of existing hand-held data entry devices used in the route delivery industry typically comprises a circuit board assembly contained within a housing. The interconnection of the processing circuitry with the display circuitry is through permanent, soldered connections. Likewise the interconnections of the central processing unit integrated circuit to data collecting random access memory, to peripheral device interface circuitry, to memory management circuitry, and to communications interface circuitry is all by permanently soldering in existing devices.
In prior art devices, machine instructions have been carried in non-dynamic memory, that is, in read only memory devices, better known as erasable programmable read only memory or EPROMS which are programmed during manufacture and are permanently installed in the existing device to control the operation of the central processing unit integrated circuit. A change in machine instructions is only accomplished by extensive retrofit of components.
Existing terminals employ processor integrated circuits which are able to process data in eight bit partitions, which, due to the nature of such eight bit architecture of the processor integrated circuit, limits the direct access of the central processing unit to 64,000 bytes of data.
In existing prior art units, electrostatic discharge protection is afforded by use of conductive metallic enclosures or by use of metallic sheathing applied to the inner walls of the enclosure of the devices, such sheathing or metallic enclosures being electrically connected to ground terminals of external devices when interconnection of hand-held data entry terminals is effectuated. Such methods of electrostatic discharge protection are susceptible to transient signals coming into the devices over interconnection circuitry from exterior units, though affording reasonable protection from transient signals created by electrostatic discharge arising on the exterior of the unit.